Magnetic recording medium

Abstract

A magnetic recording medium is provided that comprises a non-magnetic support and, in order thereabove, a radiation-cured layer cured by exposing a layer comprising a radiation curing compound to radiation, and a magnetic layer comprising a ferromagnetic powder dispersed in a binder, the radiation-cured layer comprising an inorganic powder that has been surface treated with a silane coupling agent.

1 . A magnetic recording medium comprising:
 a non-magnetic support and, in order thereabove;   a radiation-cured layer cured by exposing a layer comprising a radiation curing compound to radiation; and   a magnetic layer comprising a ferromagnetic powder dispersed in a binder,   the radiation-cured layer comprising an inorganic powder that has been surface treated with a silane coupling agent.   
     
     
         2 . The magnetic recording medium according to  claim 1 , wherein the silane coupling agent is represented by formula (1),
   X 4-n —Si—(Y) n    (1)   
       here, X denotes an alkyl group having 4 to 18 carbons, a phenyl group, a (meth)acryloxy group, or a (meth)acryloxyalkyl group having an alkyl group having 1 to 18 carbons, Y denotes OCH 3 , OC 2 H 5 , or OC 3 H 7 , and n is 2 or 3. 
     
     
         3 . The magnetic recording medium according to  claim 1 , wherein the silane coupling agent is at least one compound selected from the group consisting of hexyltrimethoxysilane, decyltrimethoxysilane, stearyltrimethoxysilane, phenyltrimethoxysilane, acryloxytrimethoxysilane, hexyltriethoxysilane, and hexyltripropoxysilane. 
     
     
         4 . The magnetic recording medium according to  claim 1 , wherein the inorganic powder that has been surface treated with a silane coupling agent is an organic solvent-dispersed silica sol. 
     
     
         5 . The magnetic recording medium according to  claim 1 , wherein the content in the radiation-cured layer of the inorganic powder that has been surface treated with a silane coupling agent is at least 30 vol % but no greater than 60 vol %. 
     
     
         6 . The magnetic recording medium according to  claim 1 , wherein the inorganic powder that has been surface treated with a silane coupling agent has an average particle size of at least 5 nm but no greater than 50 nm. 
     
     
         7 . The magnetic recording medium according to  claim 1 , wherein the magnetic recording medium comprises, between the radiation-cured layer and the magnetic layer, a non-magnetic layer comprising a non-magnetic powder dispersed in a binder. 
     
     
         8 . The magnetic recording medium according to  claim 1 , wherein the radiation curing compound is an ethylenically unsaturated compound. 
     
     
         9 . The magnetic recording medium according to  claim 1 , wherein the radiation curing compound is a polyfunctional (meth)acrylate compound. 
     
     
         10 . The magnetic recording medium according to  claim 1 , wherein the radiation curing compound is at least one compound selected from the group consisting of tricyclodecanedimethanol diacrylate, hexanediol diacrylate, and trimethylolpropane triacrylate. 
     
     
         11 . The magnetic recording medium according to  claim 1 , wherein it has a coefficient of thermal expansion of no greater than 14.0 ppm/° C. 
     
     
         12 . The magnetic recording medium according to  claim 1 , wherein the non-magnetic support is a non-magnetic support selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, and polyamide.